i have a 98 wrx wagon import and today ive notice a horrible noise, under 3k revs nothing all fine then when you plant ya foot the boost guage flutters like mad and a very fast click/knocking noise happens all the time and will not pull over 5k i dont have any warning lights on and im sure its my turbo basically warn out but i dont get any smoke no miss fireing just the very fast click/knocking, ive had down pipe of and checked for play and is minimal but obviously this doent mean the compressor side is warn and not easy to check being front entry

this only happens on boost as soon as your at 5krevs and let ya foot off its gone again

ive had this sort of noise before when a exhast cam carrier sheered its mounts but that also developed a bad missfire but this is different symptoms

any ideas would be helpful, my easiest option is try another turbo which i will do but im hoping its not a top end gone, definately not bottom end as i know what that sounds like and will remember it forever

 

been out tonight and if you accelerate without boost no noise but under boost its there so gotta be turbo im sure